The torque converter stall test helps determine if the engine is producing the correct power output. The torque converter stall test provides an engine speed for comparison with the torque converter stall engine speed that is measured at the factory. The engine stall speed should be in the range that is shown.
The torque converter stall test is designed to test the engine, the torque converter, the drive train and the brake system as a unit. The torque converter output is stalled while the engine is operated at full throttle. The speed of the engine at torque converter stall indicates whether the engine and the transmission are operating correctly under full load.
If the engine speed is lower than the normal given speed or if the engine speed is higher than the normal given speed, this indicates that there is a problem in the engine or in the transmission. If testing shows correct engine performance but the torque converter stall speed is not correct, the problem is in the torque converter or in the transmission.
Reference: To check the performance of the Caterpillar 3176C and 3196 Engines, refer to the following service literature: Specifications, SENR9527, "3176C and 3196 Engines For Caterpillar Built Machines" and Systems Operation, Testing and Adjusting, SENR9528, "3176C and 3196 Engines For Caterpillar Built Machines".
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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine. |
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The service brakes must be applied when tests are performed. Make sure that the service brakes are fully operational before you perform any tests. Make sure that the transmission oil is at the normal operating temperature of 76 to 104 °C (170 to 220 °F) when tests are performed.
Lower the work tool to the ground.
The drive wheels must not turn during the torque converter stall test. Place the machine against a solid, stationary object such as a loading dock. Engage the parking brake.
The transmission auto/manual switch must be in the MANUAL position in order to prevent any unexpected shifts during the stall test.
- Set the hydraulic fan to the maximum rpm. In order to run the hydraulic fan system at the maximum rpm, the connection to the electrohydraulic control valve for the hydraulic fan system must be disconnected.
Note: The electrohydraulic control valve is located on the right side of the engine and below the hydraulic fan pump. Turn the key start switch to the OFF position. Disconnect the electrical connector from the connection on the electrohydraulic control valve.
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| Illustration 1 | g00892580 |
- Place the transmission neutralizer override switch in the OFF position by depressing the top of the switch.
Note: For machines with the Integrated Braking System, depress the transmission neutralizer override switch once.
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| Illustration 2 | g00739087 |
- Apply the service brakes and start the engine.
Note: To ensure that the transmission oil does not overheat, do not keep the torque converter in a full stall condition for more than 30 seconds. After the torque converter is stalled, shift the transmission direction and speed control lever (if equipped) or the transmission direction control switch (if equipped) to the NEUTRAL position. Operate the engine at 1200 rpm to 1500 rpm in order to cool the oil.
- Press switch (2) for the display module until the display shows the rpm setting.
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| Illustration 3 | g00892610 |
Instrument Panel (1) Analog tachometer | |
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| Illustration 4 | g00892624 |
Control Panel (2) Switch for the display module (3) Digital tachometer | |
- Apply the service brakes with the right brake pedal and disengage the parking brake. Shift the transmission direction and speed control lever (if equipped) to the FOURTH SPEED FORWARD position. Shift the transmission direction control switch (if equipped) to the FORWARD position and depress the transmission upshift switch (if equipped) in order to engage fourth speed. Perform the torque converter stall test with the transmission in fourth speed forward. Fully depress the accelerator pedal. Allow the engine rpm to stabilize. Then, observe tachometers (1) and (3) .
The correct stall speed for the 966G Series II Wheel Loader is 2135 ± 65 rpm.
The correct stall speed for the 972G Series II Wheel Loader is 2190 ± 65 rpm.
Stall speeds that are low indicate incorrect engine performance. Stall speeds that are high indicate incorrect transmission performance or incorrect performance of the torque converter. If you must repeat the test, keep the transmission in neutral and wait for two minutes between tests.
Reference: For additional information about the Caterpillar Monitoring System, refer to the Service Manual module Systems Operation, "Monitoring System (Power Train Functions)" for the machine that is being serviced.
Reference: For additional information about the Caterpillar Monitoring System, refer to the Service Manual module Systems Operation, Testing and Adjusting, SENR1394, "Caterpillar Monitoring System".
Reference: For additional information about troubleshooting the transmission and the torque converter, refer to the Service Manual module Testing and Adjusting, "Power Train Troubleshooting" for the machine that is being serviced.